This invention relates to producing paper from which a bag may be made, having a waterproof, leakproof bottom. The paper is produced by affixing a waterproof material, such as plastic, to a portion of the bag material during the manufacturing process.
Paper bags have various and multitudinous uses, including the transporting of liquids and frozen substances which have the potential to become liquids at room temperature. Most commonly, paper bags are used to transport liquids and frozen foods from the checkout counters at grocery stores to home, and are used to transport liquids, such as soft drinks, placed in paper cups from take-out restaurants, particularly from fast food restaurants.
A common problem is the absorbency and leaking characteristics of the common paper bag. Cups containing drinks purchased from take-out restraurants leak, causing the liquid to spill into the bag, and subsequently leak through the bag, causing the liquid to subsequently spill onto cars, clothing or furniture. Meats or other groceries containing liquids, or frozen floods which begin to melt while being transported in a paper bag leak through the paper bag causing similar problems.
Until the present invention, there has not been an economical and efficient way to produce a paper bag having a bottom which is leakproof. Paper bags are inexpensive in comparison to a bag which is made of plastic, and have certain shape retention characteristics which are desirable. A device and method are disclosed herein which will produce paper from which a paper bag having a bottom which is leakproof may be made, allowing most of the bag to be made of paper, such as kraft paper, for economy and shape, while producing a bag having the desired characteristics of plastics at a lesser cost of production.
Paper bags, as commonly produced, begin from a large roll of paper such as kraft paper. Paper is fed from the roll, and slit parallel to the direction of travel of the sheet of paper as it is fed from the roll. The paper is then rolled into a continuous cylinder, glued along a seam, and cut again perpendicular to the length of the paper cylinder so as to produce a section of paper having the desired width and length for the resultant paper bag. The sides are creased and folded, and one end of the tube or cylinder is then closed by folding and gluing so as to produce the bottom, and a paper bag is created.
The present invention incorporates the well known method of producing a paper bag. The present invention improves the prior method by feeding a strip of waterproof material, such as polypropylene, through an adhesive substance, and affixing the strip of polypropylene to the roll of paper from which bags are to be produced. The width of the strip is such that the entire bottom of the bag after it is folded will be covered by the waterproof material, and further, a small portion of the side of the bag adjacent to the bottom will be covered with the waterproof material.